What Happens In the Bug: When a player in survival mode or adventure mode has their inventory open and is switched to spectator mode afterward, it leaves the inventory open, and the player can still change their inventory while in spectator mode.

What Is Suppose To Happen: What I think was suppose to happen is that the inventory menu closes while in spectator mode.

How to Recreate the Situation: Have someone change you into spectator mode while you have your inventory open.